/*
*    Licensed under the Apache License, Version 2.0 (the "License");
*    you may not use this file except in compliance with the License.
*    You may obtain a copy of the License at
*
*    http://www.apache.org/licenses/LICENSE-2.0
*
*    Unless required by applicable law or agreed to in writing, software
*    distributed under the License is distributed on an "AS IS" BASIS,
*    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
*    See the License for the specific language governing permissions and
*    limitations under the License.
*/

#pragma once

#include <algorithm>  // for min
#include <cstring>
#include <iosfwd>
#include <limits>
#include <string>
#include <sstream>
#include "base.h"

  namespace _bson {

  /**
   * A StringData object wraps a 'const string&' or a 'const char*' without copying its
   * contents. The most common usage is as a function argument that takes any of the two
   * forms of strings above. Fundamentally, this class tries go around the fact that string
   * literals in C++ are char[N]'s.
   *
   * Notes:
   *
   *  + The object StringData wraps around must be alive while the StringData is.
   *
   *  + Because string data can be used to pass a substring around, one should never assume a
   *    rawData() terminates with a null.
   */
  class  StringData {
  public:

    /** Constructs an empty string data */
    StringData()
      : _data(nullptr), _size(0) {}

    /**
     * Constructs a StringData, for the case where the length of string is not known. 'c'
     * must be a pointer to a null-terminated string.
     */
    StringData(const char* c)
      : _data(c), _size((c == nullptr) ? 0 : std::string::npos) {}

    /**
     * Constructs a StringData explicitly, for the case where the length of the string is
     * already known. 'c' must be a pointer to a null-terminated string, and len must
     * be the length that strlen(c) would return, a.k.a the index of the terminator in c.
     */
    StringData(const char* c, size_t len)
      : _data(c), _size(len) {}

    /** Constructs a StringData, for the case of a string. */
    StringData(const std::string& s)
      : _data(s.c_str()), _size(s.size()) {}

    /**
     * Constructs a StringData explicitly, for the case of a literal whose size is known at
     * compile time.
     */
    struct LiteralTag {};
        template<size_t N>
	  StringData(const char(&val)[N], LiteralTag)
	  : _data(&val[0]), _size(N - 1) {}

    /**
     * Returns -1, 0, or 1 if 'this' is less, equal, or greater than 'other' in
     * lexicographical order.
     */
    int compare(const StringData& other) const;

    /**
     * note: this uses tolower, and therefore does not handle
     *       come languages correctly.
     *       should be use sparingly
     */
    bool equalCaseInsensitive(const StringData& other) const;

    void copyTo(char* dest, bool includeEndingNull) const;

    StringData substr(size_t pos, size_t n = std::numeric_limits<size_t>::max()) const;

    //
    // finders
    //

    size_t find(char c, size_t fromPos = 0) const;
    size_t find(const StringData& needle) const;
    size_t rfind(char c, size_t fromPos = std::string::npos) const;

    /**
     * Returns true if 'prefix' is a substring of this instance, anchored at position 0.
     */
    bool startsWith(const StringData& prefix) const;

    /**
     * Returns true if 'suffix' is a substring of this instance, anchored at the end.
     */
    bool endsWith(const StringData& suffix) const;

    //
    // accessors
    //

    /**
     * Get the pointer to the first byte of StringData.  This is not guaranteed to be
     * null-terminated, so if using this without checking size(), you are likely doing
     * something wrong.
     */
    const char* rawData() const { return _data; }

    size_t size() const { fillSize(); return _size; }
    bool empty() const { return size() == 0; }
    std::string toString() const { return std::string(_data, size()); }
    char operator[] (unsigned pos) const { return _data[pos]; }

    /**
     * Functor compatible with std::hash for std::unordered_{map,set}
     * Warning: The hash function is subject to change. Do not use in cases where hashes need
     *          to be consistent across versions.
     */
    struct Hasher {
      size_t operator() (const StringData& str) const;
    };

    //
    // iterators
    //

    typedef const char* const_iterator;

    const_iterator begin() const { return rawData(); }
    const_iterator end() const { return rawData() + size(); }

  private:
    const char* _data;        // is not guaranted to be null terminated (see "notes" above)
    mutable size_t _size;     // 'size' does not include the null terminator

    void fillSize() const {
      if (_size == std::string::npos) {
	_size = strlen(_data);
      }
    }
  };

  inline bool operator==(const StringData& lhs, const StringData& rhs) {
    return lhs.compare(rhs) == 0;
  }

  inline bool operator!=(const StringData& lhs, const StringData& rhs) {
    return lhs.compare(rhs) != 0;
  }

  inline bool operator<(const StringData& lhs, const StringData& rhs) {
    return lhs.compare(rhs) < 0;
  }

  inline bool operator<=(const StringData& lhs, const StringData& rhs) {
    return lhs.compare(rhs) <= 0;
  }

  inline bool operator>(const StringData& lhs, const StringData& rhs) {
    return lhs.compare(rhs) > 0;
  }

  inline bool operator>=(const StringData& lhs, const StringData& rhs) {
    return lhs.compare(rhs) >= 0;
  }

  /* inline std::stringstream& operator<<(std::stringstream& stream, const StringData& value) {
        stream << value.toString();
        return stream;
	}*/
  /*
    std::ostream&  operator<<(std::ostream& stream, const StringData& value) { 
        assert(false);  
        return stream;
	}*/

  }

#include "string_data-inl.h"
